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SQL Puzzle | Comma Separated String – The SWAP Puzzle | Advanced SQL

In this puzzle you have to swap the first two letters of the comma separated string. For more details please see the sample input and expected output.

Sample Input

Id Vals
1 a,b,c
2 x,y,z

Expected Output

Id Vals
1 b, a, c
2 y, x, z

Script – DDL and INSERT Sample Data

--

CREATE TABLE MultipleVals 
(
	 Id INT
	,[Vals] VARCHAR(100)
)
GO


Insert Into MultipleVals values 
 (1,'a,b,c')
,(2,'x,y,z')
GO

SELECT * FROM MultipleVals
GO

--

SOLUTION 1 | CROSS APPLY & XML

--

SELECT 
	  Id
      ,CONCAT(n.value('/a[2]','VARCHAR(5)'),', '+n.value('/a[1]','VARCHAR(5)'),', '+n.value('/a[3]','VARCHAR(5)'))
	  Vals
FROM  MultipleVals A
CROSS APPLY 
(
	SELECT *
	FROM (SELECT CONVERT(XML, ('<a>' + REPLACE([Vals],',','</a><a>')+'</a>'))n )X 
)z

--

OUTPUT – 1 | CROSS APPLY & XML

--

Id          Vals
----------- -------------------
1           b, a, c
2           y, x, z

(2 rows affected)

--

SOLUTION 2 | USING ParseName

--

SELECT Id,
       CONCAT
	   (
		   PARSENAME(REPLACE([Vals],',','.'),2), ', ' ,
		   PARSENAME(REPLACE([Vals],',','.'),3), ', ' ,
		   PARSENAME(REPLACE([Vals],',','.'),1) 
	   ) Vals
FROM MultipleVals

--

OUTPUT – 2 | PARSE NAME

--

Id          Vals
----------- -------------
1           b, a, c
2           y, x, z

(2 rows affected)


--

SOLUTION 3 | Cross APPLY & STRING_SPLIT

--

SELECT Id, 
CONCAT
(
  MAX(CASE WHEN X.rnk = 2 THEN x.Vals END),', '
, MAX(CASE WHEN X.rnk = 1 THEN x.Vals END),', '
, MAX(CASE WHEN X.rnk = 3 THEN x.Vals END) 
) Vals
FROM MultipleVals V
CROSS APPLY
(
	SELECT Value Vals , ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) rnk FROM 
	STRING_SPLIT(V.Vals,',')
)x
GROUP BY Id

--

OUTPUT – 3 | Cross APPLY & STRING_SPLIT

--

Id          Vals
----------- ----------------------
1           b, a, c
2           y, x, z

(2 rows affected)

--

Enjoy 🙂

Please add comment(s) if you have one or multiple solutions in mind. Thank You.

Pawan Khowal

Pawan is a SQL Server Developer. If you need any help in writing code/puzzle or training please email at – pawankkmr”AT”gmail.com. Meanwhile please go throgh the top pages from his blog.

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